On May 18, 1927, a man named Andrew Kehoe blew up the school in Bath Township, Mich. Most of the 44 killed were children. It remains the deadliest attack on a school in U.S. history. It is also regularly left out of accounts of terrorism in America.
Kehoe, an electrician, had previously worked on the school and had rigged explosives through the buildings in the weeks leading up to the attack. His timer device in one part of the building failed, so children in those rooms survived. In the immediate aftermath of the school explosion, Kehoe set off another bomb in his car, killing himself and several others nearby. Prior to the school explosion, he had murdered his wife and set his own farm on fire. His motive was anger at a foreclosure on his farm, and the taxes levied by the township to pay for the new school.